Method and apparatus for producing seamless sharp bends in wave guide tubing to replace mitered soldered bends



May 20, 1958 F. J. FUCHS, JR 2,835,306

METHOD AND APPARATUS FOR PRODUCING SEA'MLESS SHARP BENDS IN WAVE GUIDE TUBING T0 REPLACE MITERED SOLDERED BENDS Filed Aug. 20, 1952 2 Sheets-Sheet 1 as if 0 O 5/ o a" a5 W x 2; 613! o if f INVENTOR ATTORNEY May 20, 1958 F. J. FUCHS, JR 2,335,306

METHOD AND APPARATUS F OR PRODUCING SEAMLESS SHARP BENDS IN WAVE GUIDE TUBING TO REPLACE MITERED SOLDERED BENDS Filed Aug. 20, 1952 2 Sheets-Sheet 2 INVENTOR BY M ATTORNEY Unit Francis Joseph Fuchs, lira, Winston-Salem, N. C., as-

signor to Western Electric Company, Incorporated, New Ynrk, N. Y., a corporation of New York Application August 20, 1952, Serial No. 305,325

8 Claims. (Cl. 153-41) This invention pertains to methods of and apparatus for bending wave guide tubing and more particularly to methods of and apparatus for producing seamless sharp bends in wave guide tubing.

In the bending of wave guide tubing it is essential that the internal dimensions of the finished wave guides be uniform throughout and that both the internal and external surfaces be smooth. in the past, sharp bends in wave guide tubing have been produced by mitering three separate sections of tubing at the desired angles and joining them by brazing the joints. This is a costly procedure and unsatisfactory because a discontinuity is formed in the wall of the wave guide where the sections are brazed which affects the transmission qualities of the wave guide transmission line and reduces the transmission efiiciency of the line.

It is an object of the present invention to economically bend wave guide tubing from a single integral piece so as to have no discontinuities therein.

Another object of this invention is to provide a tube bending apparatus having improved dies and mandrels so that the wave guides are formed with a minimum distortion of the material of the tubing and with few imperfections therein.

In order to obtain these and other objectives, and in accordance with the general features of the invention, one embodiment provides an apparatus having three bending operations, each bending operation performing one step in the formation of the finished wave guides. The first operation involves a pair of dies having complementary curved faces for receiving a partially bent wave guide tubing, two side engaging mandrels curved complementary to the faces of the dies and means for moving the dies into engagement with the external walls of the tubing and simultaneously moving the side engaging mandrels into contact with the internal walls of the wave guide tubing. The second bending operation involves dies having complementary angular sinks for supporting the external Walls of the Wave guide tubing, side engaging mandrels having pivoted cam blocks there in for supporting the internal walls of the wave guide tube and means for moving the dies into engagement with the wave guide tubing and simultaneously moving the side engaging mandrels into the interior of the wave guide tubing thereby causing the pivoted blocks to cam into engagement with the internal walls of the tubing.

The third operation produces a transverse corrugation in the formed wave guide and comprises means for supporting a bent wave guide, the said supporting means having a transverse groove therein, and a movable die whose face is shaped complementary to the transverse groove in said supporting means.

Other novel features and advantages of the present invention will become apparent in the following description when considered in conjunction with the accompanying drawings, wherein:

Fig. 1 is a plan view of a bending apparatus performing the first step of the bending operation;

assists Patented May 20, 1958 guide tubing shown therein in cross section: and

Fig. 5 IS an enlarged perspective view of a completed Wave guide bent by the apparatus disclosed in Figs. 1-4, inclusive; and

Fig. 6 is a perspective view of a section. of preformed wave guide tubing prior to bending in accordance with the teaching of the present invention.

Referring now to the drawings, and in particular to Fig. 6, a piece of partially bent wave guide tubing 13 is shown ready for the first bending operation in accord ance with the present invention.

Attention is next directed to Fig. 1 in which a bending apparatus 10 is shown after the completion of a first step in the bending of a wave guide. A base 11 of the bending apparatus ltl has secured thereon a stationary diev 'mandrels into contact with the internal walls of the wave guide tubing 15. Two guide blocks 21 are secured to the base 11 and guide the movable die 16 therebetween and into contact with the left side external wall. of the wave guide tubing 15. The guide blocks 21 also cooperate with angularly positioned faces 22 of the stationary die 12 to guide the mandrels 18 into engagement with the internal walls of the wave guide tubing 15.

Attention is next directed to Fig. 2 wherein bending apparatus 29 is shown in an open or retracted position prior to a bending operation. A base 30 of the machine 29 has mounted thereon a concave die consisting of stationary die sections 31 and a movable die section 32. A pin 28 is attached to the base 30 and guides the movable die section 32 into engagement with the right side external Wall of the wave guide tubing 15 when the movable die section 32 is actuated by a piston 34 during the bending operation. Slidably mounted on the base 30 is an operating head 35 which has a guide slot cooperatin with two upright guide pins 36 secured in the base to accurately determine the movement of the operating head. Secured to a projecting central portion of the operating head 35 is a convex forming die 37 which engages the concave or left side external wall of the Wave guide tubing ifs when the operating head 35' is moved toward the right by a piston 33 substantially simultaneously with the actuation of die section 322 by the piston 34. At the same time that the convex movable die 37 is actuated, faces 39 of the operating head 35 engage two angularly positioned compound mandrels 4i) and force them against the internal walls of the wave guide tubing 15. Each of the mandrels includes a retaining sleeve 41 that is secured to the base 3t and which encloses reciprocable arm 42 and operating member 43. The reciprocable arms 42 and the operating members 43 are in longitudinal sliding contact with each other and are held in this position by the retaining sleeves 41. Concave arcuate portions of the reciprocable arms 42 are positioned within the wave guide tubing 15 and arcuate cam blocks 44 nest therein. When the operating head 35 moves toward the right, the faces 39 thereof contact the operating members 43 of the mandrels 4i and moves them longitudinally in the retaining sleeves 41 until the beveled faces 49 of the operating members 43 contact the cam blocks 44. The cam blocks M are then pivoted into engagement with the left side internal wall of the wave guide to support it during bending. The operating head 35 also engages the reciprocable arms 42 and moves them longitudinally into contact with the right side internal wall of the wave guide 15 to support it during bending.

Referring now to Fig. 4, a supporting die 45 is attached to a base 46 and holds the partially formed wave guide 15 on its upper surface which has therein a transverse groove 48. A corrugating die h is attached to a piston 5'1 and is movable into contact with the partially formed wave guide 15. A cylindrical member 53 of the corrugating die Sh cooperates with the transverse groove 48 in the supporting die 43 to produce a corrugation 55 (Fig. 5) in the Wave guide when the piston 51 is actuated. Circular portions 54 of the corrugating die 50 engage and support the side walls of the wave guide 15 c during the corrugating operation.

Although the invention has been described with reference to a particular embodiment, it is to be understood that various modifications may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An apparatus for bending \l-shaped wave guide tubes comprising a base, reciprocable dies slidably mounted on said base, means for moving said dies into engagement with the external Walls of a wave guide tube, reciprocable arms extending into said wave guide tube; said arms having therein arcuate recesses located adjacent the portions of the Wave guide tubing which are engaged by one of said reciprocable dies, earn means pivotally nested in said arcuate recesses, means actuated by said die moving means for forcing said reciprocable for contacting an internal wall of the section of Wave guide tubing being bent, said reciprocable arm having a concave arcuate portion adjacent said curved end, a cam block pivotally nested in said concave arcuate portion and engageable with a tubing wall subjected to bending, an operating member enclosed in said retaining sleeve and in longitudinal sliding contact with said reciprocable arm, said operating member having a beveled face for engaging said cam block and pivoting it into engagement with an internal wall of the section of wave guide tubing during bending.

3. An apparatus for bending a section of wave guide tubing comprising a base, a first movable die section slidably mounted thereon, stationary die sections cooperating with said first movable die section to support the convex side of the section of wave guide tubing being bent, an operating head, a second movable die section attached thereto, and a plurality of mandrels movable into supporting contact with the internal walls of said section of wave guide tubing by said operating head, said mandrels each comprising a reciprocable arm adapted to be contacted by said operating head, an arcuate cam block pivotally nested in said reciprocable arm, an operating member in longitudinal sliding contact with the arcuate earn block to pivot it into contact with the internal walls of the wave guide tubing at a position opposite the second movable die section when said operating member is contacted by said operating head, and a retaining sleeve secured tosaid base to guide said reciprocable arm and said operating member into the wave guide and to retain said reciprocable arm and said operating member in longitudinal sliding contact.

4. An apparatus for bending wave guide tubes comprising a base; a concave die mounted thereon, said concave die including two stationary die sections and a first movable die section therebetween; means for moving said first movable die section into contact with a wave guide tube to be bent; a plurality of mandrels for supporting the internal walls of the wave guide tube during bending, each mandrel including an operating member, a reciprocable arm in slidable contact with said operating member and having a concave arcuate portion therein, and a cam block nested in said concave arcuate portion and adapted to be cammed into engagement with the internal walls of the wave guide tube by said operating member; an operating head including a second movable die section attached thereto for cooperating with said concave die to bend the wave guide tube, and contact faces formed integral with the operating head to contact said operating members and said reciprocable arms to force the reciprocable arms into engagement with the internal walls of said wave guide tube and the cam blocks into opposition to the second movable die section; and means to actuate said operating head to bend said wave guide tube.

5. In an apparatus for bendin a Wave guide tube, a base, external dies mounted thereon, reciprocable means for moving said external dies into engagement with external surfaces of opposite walls of a wave guide tube, internal die means extending into said Wave guide tube and having first sides thereof formed complementary to a first of said external dies to engage an internal surface of a first Wall of the Wave guide tube adjacent said first external die, second sides of said internal die means having concave arcuate portions positioned inside the wave guide tube, forming cams nested in said concave arcuate portions for engaging an internal surface of a second wall of said wave guide tube adjacent a second of said external dies, and operating members actuated by said reciprocable means to pivot said forming cams into engagement with said second wall of the wave guide tube.

6. Apparatus for bending a wave guide tube, which comprises reciprocable external dies operable for engaging opposite external walls of a wave guide tube, a plurality of mutually cooperating pivotable cams, support means for holding the cams within the wave guide tube in positions opposite to and cooperating with one of said external dies, said support means being designed also to support the interior of the wave guide tube adjacent to another of said external dies, and means operable when the external dies move into engagement with the external walls for simultaneously actuating the cams pivotally to cause the cams to engage the interior of the tube adjacent to said first-mentioned external die so as to cooperate therewith to modify the configuration of the wave guide tube.

7. The method of producing a modified, generally V-shaped bend of substantially uniform internal cross section in rectangular Wave guide tubing, which comprises preforming a generally arcuate-shaped bend of a desired angle in a section of the wave guide tubing, flattening a portion of the convex wall of the bent wave guide tubing, said flattened portion being disposed symmetrically with respect to the center of the initial bend, to produce an outer angular surface while supporting the tube externally and internally to prevent any other change in the configuration of the wave guide tube, and flattening a lesser portion of the concave wall of the wave guide tubing, said last-mentioned flattened portion being disposed symmetrically about the center of the initial bend and substantially parallel to said first-mentioned flattened portion to produce an inner angular surface while sup porting the tube externally and internally to prevent any other change in the configuration of the wave guide tubing.

' 8. The method of producing a modified, generally V-shaped bend of substantially uniform internal cross section in rectangular wave guide tubing, which comprises preforming a generally arcuate-shaped bend of a desired angle in a section of the wave guide tubing, flattening a portion of the convex wall of the bent wave guide tubing, said flattened portion being disposed symmetrically With respect to the center of the initial bend, to produce an outer angular surface while supporting the tube externally and internally to prevent any other change in the configuration of the wave guide tube, flattening a lesser portion of the concave wall of the wave guide tubing, said last-mentioned flattened portion being disposed symmetrically about the center of the initial bend and substantially parallel to said first-mentioned flattened portion, to produce an inner angular surface while supporting the tube externally and internally to prevent any other change in the configuration of the wave guide tub- 6 ing, and forming concave indentations extending transversely of the tube along the corners of the outer angular surface of the wave guide tubing.

References Cited in the file of this patent UNITED STATES PATENTS 116,012 Beecher June 20, 1871 375,577 Short Dec. 27, 1887 1,239,177 Granz Sept. 4, 1917 1,633,744 Hughes June 28, 1927 1,923,272 Maroto Aug. 22, 1933 2,085,057 Williams June 29, 1937 2,411,338 Roberts Nov. 19, 1946 2,435,294 Schwinn Feb. 3, 1948 2,512,849 Cork et al June 27, 1950 2,516,372 Cross July 25, 1950 FOREIGN PATENTS 1,053,169 France Sept. 30, 1953 

